Why you can’t see the stars your grandparents could

If you go stargazing tonight, the sky you see will probably be considerably less magnificent than the sky your grandmother looked at.

Scientists from Germany, Israel, Italy and the U.S. recently published a new atlas showing that 99 percent of U.S. and Europe, and 80 percent of the world, looks up at skies polluted by artificial lights.

"Most of the world is affected by this problem, and humanity has enveloped our planet in a luminous fog that prevents most of Earth’s population from having the opportunity to observe our galaxy," write the study's authors.

Scientists (and regular people) have known about light pollution for a long time. But this is the first time that scientists created an actual numbers-based system to measure how light pollution is affecting the world (yay! and aw).

The scientists published a map showing how artificial light affects what people can see in the night sky. (Photo: Science Advances)

"Despite the increasing interest among scientists in fields such as ecology, astronomy, health care, and land-use planning, light pollution lacks a current quantification of its magnitude on a global scale," the researchers explained.

According to the new atlas, Italians and South Koreans have to deal with the most polluted skies, while Canadians and Australians get the least pollution.

And if you want to stargaze, get out of the U.S. Eighty percent of Americans can't see the Milky Way. Instead, go to India or Germany – people from these two countries can see the Milky Way most clearly, while residents of Saudi Arabia and South Korea are most likely to be stuck in the dark when it comes to seeing stars.

All this light pollution is obviously a problem for stargazers and astronomers. But it's an even bigger problem for nocturnal animals, who aren't adapted for such a bright night. To go a step further, all animals are affected somewhat, since they have circadian rhythms that are kept in line by predictable light and dark cycles (that's how our bodies know when to do things like sleep and eat).

"It is possible to imagine two scenarios for the future," the study's authors point out. "Perhaps the current generation will be the final generation to experience such a light-polluted world, if light pollution is successfully controlled. Alternatively, perhaps the world will continue to brighten, with nearly the entire population never experiencing a view of the stars, as in Isaac Asimov’s 'Nightfall' novel and short story," continue the scholar-poets. The future may literally be a dark one.

On the "bright" side, if you're a stargazer, then this is a great excuse for you to take a trip to India.

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Ilana Strauss
writes about social sciences and the environment because she is a person on a planet.